From
The Srimad-Bhagavad-Gita: The Revelation of the Supreme Self
Translated by Swami Premananda
Whosoever with devotion offers me a leaf, a flower, a fruit, or water, I accept it from him as the devout gift of a pure heart.
O son of Kunti, whatever thou doest, whatever thou eatest, whatever thou offerest as oblation, whatever thou givest as gift, and whatever soul’s power thou puttest forth, do it as an offering unto me.
When a gift is offered with the thought that it is righteous to perform acts of charity, without expecting anything in return, at the right time and place and to a worthy person, that gift is regarded as the source of self-liberation and peace.
That gift which is made with the hope of receiving in return, or desiring personal reward, or with reluctance, is known as the source of pride and sorrow.
The gift that is given at the wrong place or time, to unworthy persons, or ungraciously and with contempt, is the cause of self-degradation and misery.
From Ch 9:26-27 and Ch 17:20-22